Timing escapement mechanism



Dec. 20, 1966 A. L. KORR 3,292,438

TIMING ESCAPEMENT MECHANISM Filed Feb. 2, 1965 United States Patent Office Patented Dec. 20, 1966 3,292,438 TIMING ESCAPEMENT MECHANISM Abraham L. Korr, Philadelphia, Pa., assignor to the United States of America as represented by the Secretary of the Army Filed Feb. 2, 1965, Ser. No. 429,931 2 Claims. (Cl. 741.5)

The invention described herein may be manufactured and used by or for the Government for governmental purposes without the payment to me of any royalty thereon.

The present invention relates to mechanical timers or clocks of the type used to provide control functions according to elapsed time while a moving body, such as artillery shell, travels between two points in a flight path or trajectory. Such timers are thus subjected to the same forces as the moving body or flight vehicles in which they are mounted or by which they are carried. These forces may result from napid acceleration or setback, rapid directional changes, high speed rotation or spin, and the like. By reason of definite adverse effects on the moving parts thereof, these forces can affect the accuracy of the timer and even stop its functioning in some cases.

Conventional timers of the above type, are used for controlling the operation of artillery shell fuzes and other precise timing functions in moving bodies of the type referred to. Such timers include a timer source of energy which is generally a wound mainspring, an actual time meansuring assembly which is generally a timing escapement mechanism, and a connecting reduction gear train between the energy source and the said escapement mecha nism, and a connecting reduction gear train between the energy source and the said escapement mechanism.

The present invention, relates more particularly to timing escapement assemblies or mechanisms for mechanical timers and clocks of the type referred to, and has for its primary object to provide an improved timing escapement mechanism which is extremely stable and accurate in its timing functions under a wide range of different externally-applied forces.

It is also an object of this invention to provide an improved and simplified timing escapement mechanism which meets extreme spin and setback or acceleration conditions in connections with the timing of fuzes for modern highspeed artillery shells and like projectiles in flight, without impairment of the timing function.

The escapement assembly or mechanism, in accordance with the invention, is of the type having a rotary escapement wheel and a pivoted escapement lever with the usual two-bladed escapement means or pallets, arranged in balanced relation about the pivot axis of an operating shaft or arbor in a generally conventional manner to control the step-by-step rotary movement of the escapement wheel. The latter is connected through a gear train with a controlled mechanism and driving spring or other energy source for the escapement mechanism and timer.

Further in accordance with the invention, the pivoted escapement lever is without the usual oscillating masses or Weights with which it is usual-1y equipped. Likewise there is no escapement spring or hair spring for controlling the oscillation of the escapement lever. Instead, the pivoted escapement lever is made in the form of a permanent magent having a north pole at one end and a south pole at the other on opposite sides of the pivot axis. The ends of the escapement lever then oscillate back and forth between two fixed spaced magnets presenting poles of like polarity thereto at each end, thereby to provide effectively magnetic repulsion as the poles are approached by the lever in oscillating back and forth.

The controlling magnets, two in number at each end of the lever arm, are spaced adjustably to provide a predetermined air gap in which the ends of the lever arm oscillate. The two magnets are laterally oriented so that when the lever arm is at rest it will lie mid-way between them. Retaining means is provided for holding the lever arm close to one magnet or one set of magnets before starting operation and is capable of movement either mechanically, or by centrifugal or setback forces. The pallets of the lever escapement may have the same configuration as conventional design to engage the teeth of the escapement wheel in the normal or conventional manner.

Thus once the restraining means is removed the like magnetic poles of the permanent magnets repel the lever arm in the direction of the opposite pole and the escapement lever pivots through its usual short arc. The first pallet element disengages itself from the escapement wheel and the second pallet approaches its point of engagement and will engage a corresponding tooth due to the energy applied through the gear train or other connection with the driving force or spring which forms part of the timing element. The lever arm will then be close to the second like polarity repulsion position and will move in reverse to start a new cyclic movement of the escapement lever. The magnetic forces obey the inverse square law and therefore are most effective as the two like magnetic poles come closest together.

By this simplification of the escapement mechanism it is made substantially spin-insensitive. The escapement spring and the escapement weights or masses are reduced to zero, thus there is no escapement spring or lever weights on which centrifugal and other forces may act as in the usual case with conventional mechanical escapement mechanisms of this type. A timer or clock provided with a timing escapement mechanism embodying the invention will thus function accurately about a set time over a relatively wide spin range and is thus well adapted for use in timing systems for modern high speed artillery shells and the like.

The invention, will however, be further understood from the following description, when considered with reference to the accompanying drawing showing a certain embodiment thereof, and its scope is pointed out in the appended claims.

In the drawings:

FIG. 1 is a plan view of a timing escapement mechanism embodying the invention as applied to an artillery shell fuze or like moving body adapted for travel in a flight path or trajectory in space,

FIG. 2 is a side view, in elevation, of the fuze or moving body of FIG. 1, showing the location therein of the timing escapement mechanism as the time base control element thereof,

FIG. 3 is a cross sectional view, in elevation, of the pivot and pallet section of the escapement lever of the mechanism of FIG. 1, taken on the section line 33 thereof, showing further details of construction, and

FIGS. 4, 5, and 6 are fragmentary plan views, similar to that of FIG. 1, showing the timing escapement lever in various positions in its oscillatory path for control of the escapement wheel in accordance with the invention.

Referring to the drawing, wherein like elements throughout the various figures are designated by like reference numerals and characters, and referring particularly to FIGS. 1 and 2, a cylindrical section ltlof the outer casing or frame of a moving body adapted fortravel in a flight path or trajectory in space is provided with a hollow interior or chamber 11 in which is located a timing escapement mechanism 12 in accordance with the invention.

The mechanism comprises an escapement Wheel 14 which may, as indicated, be of a conventionl construction with a plurality of equal, spaced, radial escapement teeth having sloping pallet-actuating end surfaces 16. The wheel is mounted to rotate on a pivot shaft 17 in connection with a pinion gear 18 which may form part of a gear train, as indicated by the gear 19, connecting the escapement wheel with a controlled timed mechanism such as a fuze timer 20, for example. The connection between the escapement wheel gear train and the timed mechanism is indicated by the dot-and-dash line 21. This connection may include a source of energy for driving or biasing the escape wheel to rotate in one direction as indicated by the arrowed line adjacent thereto, and may be in any suitable form such as a coiled helical spring 22 indicated in the connection 21. Since the timed mechanism is not part of the present invention, further description is not believed to be necessary.

A pivoted escapement lever 24, having 'two effectivelyradial and oppositely-disposed lever arms 25 and 26, is mounted, together with two-bladed escapement means or pallets 27 and 28, to oscillate about a pivot axis 29 provided by an operating arbor or shaft 30. The pallets are positioned to control the step-by-step rotary movement of the escapement wheel 14 as they knife alternately in and out of the tooth periphery of the wheel. As is understood, the trailing pallet 28 receives a thrust from each tooth via the cam surface 16, thus keeping the lever and the pallets oscillating about the axis 29 from the energy received through the control and driving connection 21 from the source 22.

The arbor 30 and the lever 24, together with the pallets 27 and 28, are rigidly assembled to form the relatively simple and like-weight magnetic escapement mechanism 12. The arbor is pivotly mounted in upper and lower tapered bearing means provided in fixed supporting blocks 32 and 33, as viewed in FIG. 3 for example. Due to its light weight and lack of springs, the arbor 30 of the escapement mechanism may lie outside the axial movement of the body or carrier, which is the axis of spin in the present example, assuming the casing section 10 to be that of an artillery shell fuze mounting on the forward end of an artillery shell indicated in fragmentary dotted line at 13 in FIG. 2.

In accordance with the invention, the escapement lever 24 is not weighted or escapement-spring controlled as is conventional. Instead it is effectively a bar magnet of the permanent type having one polarity, such as South, at the outer free end of one lever arm 25 and the opposite polarity, such as North, at the outer free end of the opposite lever arm 26. Considered further, the escapement lever has two radial and oppositely-disposed magneticallypolarized arms. The two-bladed pallet, or escapement means, is arranged with these arms in balanced relation about the axis of the operating shaft or arbor 30 to control the rotation of the escapement wheel 14 which is spring driven or otherwise biased to rotate in one direction in connection with the controlled apparatus such as the fuze timer 20.

For magnetic control, instead of dynamic spring and weight control, the polarized ends of the bar-magnet escapment lever oscillate between opposed magnetic poles of like polarity with the magnetic repulsion action in place of mass and escapement spring control.

Thus in accordance with this system, tw-o permanent bar magnets 35 and 26 are mounted in opposed spaced, end-to-end relation to each other at the outer or polar ends of the arm 25 and on opposite sides thereof in a common plane with the lever to provide a magnetic field or gap in which the polar end moves in the range indicated to closely approach, without touching, the like-poled, opposed, spaced ends of the magnets. The repulsion action and clearance is adjustable by moving the magnets 35 and 36 toward and away from each other by suitable means. In the present example a slotted base plate 37 and retaining screw 38 are provided for this purpose in connection with each magnet, as indicated. These may be secured to the inner wall of the well 11 of the carrier or body 10 of the present example.

Likewise, to add to the control action by magnetic repulsion, the opposite arm 26 is provided with a similar pair of spaced bar magnets 39 and 40, and similarly adjustable with respect thereto by a slotted base plate 41 and retaining screws 42 provided thereon and secured to t the inner wall of the well 11.

The two opposed, spaced permanent magnets at opposite ends of the magnetic escapement lever, are laterally oriented so that the lever arms, at rest, lie substantially midway between the opposed like poles thereof. The controlling magnetic means which includes the two sets of spaced magnets, is preferably of the permanent barmagnet type indicated, for simplified light-weight construction.

Means are also provided for holding the lever in a starting position, as indicated in FIG. 1, with the polar ends of the arms 25 and 26 in close spaced relation to the magnets 35 and 40 respectively. The holding or starting means may be a pin or any device suitable for the purpose of holding the lever arm polar ends close to the magnetic poles, as shown, in a position for maximum repulsion force. Such holding means must be capable of removal either mechanically, or by centrifugal or setback forces employed. In the present example, a spring arm 45 in the carrier is provided with a latch 46 and positioned to engage and hold the polar or free end of the lever arm 25, as indicated, with the lever in one extreme travel or rotational position shown. The latch is actuated by centrifugal force acting on a metal block or weight 47 carried by the arm 45 to move in the direction of the arrow as the carrier or casing 10 spins in flight.

Thus when the restraining means or latch 46 is removed, the closely spaced north poles act in repulsion on the lever arm 26 and cooperate with a similar repulsion action provided by the closely-spaced south poles acting on the lever arm 25. This action tends to rotate the escapement lever toward the other extreme of its rotational or oscillatory swing or movement about the pivot axis or shaft 30 in the direction indicated by the arrow at the end of the lever 26 in FIG. 1 and to the lever arm positions outlined at 25a and 26a.

Considering the teeth 15 of the escapement wheel 14 that are actively engaged with the pallets 27 and 28 as the lever 24 rotates or oscillates, four may be designated in FIG. 1 and in FIGS. 4, 5, and 6 at A, B, C and D. In FIG. 1, the pallet blade 27 is clear of the tooth D and will cover and will come into contact with the tooth C as.

the wheel rotates. The pallet blade 28, in contact with the tooth A, having just stopped the rotation of the wheel, now starts to release the tooth A as the lever arm swings away under the repulsion action of the magnetic force.

Moving to mid-way of its swing or oscillatory travel both pallet blades are clear of the teeth A, B, C and D, as the escapement wheel rotates from the position shown in FIG. 1 to that of FIG. 4. The cam surface 16 on the tooth A imparts the dynamic push to the pallet blade 28 i as is conventional to keep the lever in oscillatory motion as a continuing movement in the direction of the opposite limit of travel indicated by the arrow.

FIG. 5 shows the lever arms of 25 and 26 at the opposite ends of their oscillatory movement, in close spaced repelling relation with the poles of the magnets 36 and.

shaft 17 through the gearing 19 is permitted to advance through a time cycle 'by the step-by-step movement of this simplified time escapement mechanism. The next step at the end of the movement in the new direction carries the lever back to the starting position shown in FIG. 1 with the wheel against start. A new cycle then follows as a repetition of the stepping action above described.

From the foregoing description it will be seen that the timing escapement mechanism is of the type having a spring driven or biased toothed escapement wheel which rotates in one direction on a fixed pivot axis provided by a drive shaft by which it is carried and adapted to be connected with a controlled device or timer, and a pivoted escapement lever with oscillating pallet means engaging the wheel to control its movement.

The escapement lever is effectively a bar magnet of the permanent magnet type having one polarity at one end and the opposite polarity at the opposite end, with two permanent magnets or the like as magnetic means providing two magnetic poles or like polarity with the lever at each end thereof. The magnetic means is mounted in such a manner that the poles are in opposed spaced relation to each other at the outer polar ends of the lever and at opposite sides thereof, in a common plane with the lever, to provide a magnetic field or gap in which each polar end of the lever oscillates to closely approach like spaced magnetic poles with an increasing repulsion action. Thus without weights or extra mass in the lever arms of the escapement lever and without the use of additional escapement springs and wholly by simple magnetic means, the pivoted escapement lever is caused to oscillate and actuate the escapement wheel through the pallet control as described. Moving parts most aifected by the forces acting on the moving body by which the mechanism is carried are thus eliminated from the mechanism by the improved magnetically polarized escapement lever and repulsion magnet control thereof.

I claim:

1. A timing escapement mechanism comprising in combination, a rotary escapement wheel, means providing a spring-loaded driving connection with said wheel, an oscillatory pivoted escapement lever with connected pallet blades operatively engaging said escapement wheel to control its rotational movement, said escapement lever being magnetically-polarized with opposite magnetic poles at the outer free ends thereof and being mounted to oscillate about a fixed pivot axis normal to the plane thereof, means providing spaced magnetic poles in said plane in spaced relation to the outer polar ends of said lever and of like polarity therewith for applying a magnetic repelling force thereto at each end with each oscillatory excursion thereof, said means including two permanent bar magnets mounted in opposed spaced end-to-end relation to each other at each outer polar end of the lever on opposite sides thereof, and releasable means for holding the lever in a locked position at the end of one oscillatory excursion with the magnetic repelling force acting upon the lever at substantially maximum magnitude, said releasable means being responsive to externally applied force resulting from accelerated movement of said mechanism and acting in a predetermined direction with respect to the pivot axis thereof.

2. In a time-control apparatus, a timer escapement mechanism comprising in combination, a rotary toothed escapement wheel, a pivot shaft on which said lever con nected with said wheel is mounted and with which it rotates, means providing a driving connection with said shaft for timing control of said apparatus, means in said connection for applying a biasing force to said escapment wheel for rotational movement in one operational direction, an oscillatory pivoted escapement lever connected with said wheel to control its operational movement, said escapement lever having two radial and oppositely-disposed magnetically-polarized lever arms of opposite polarity at the outer free ends thereof and being mounted to oscillate about a fixed pivot axis normal to the plane of the lever arms thereof, and means providing spaced magnetic poles in said plane in spaced relation to the outer polar ends of said lever arms and of like polarity therewith for applying a magnetic repelling force to both arms of the lever at the ends of the oscillatory excursions thereof.

References Cited by the Examiner UNITED STATES PATENTS 2,061,047 11/1936 Schweitzer 58117 2/1965 Popovitch 741.S

RICHARD B. WILKINSON, Primary Examiner.

G. F. BAKER, Assitant Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No 3 ,292 ,438 December 20 1966 Abraham L. Korr It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

In the drawings, the polarity markings on elements 39 and 40 1n Fig. 4, on element 40 in Fig. 5, and on element 26 in Fig. 6, for "S" read N column 3, line 65, for "26" read 36 Signed and sealed this 14th day of November 1967.

(SEAL) Attest:

Edward M. Fletcher, 11'.

EDWARD J. BRENNER Attesting Officer Commissioner of Patents 

1. A TIMING ESCAPEMENT MECHANISM COMPRISING IN COMBINATION, A ROTARY ESCAPEMENT WHEEL, MEANS PROVIDING A SPRING-LOADED DRIVING CONNECTION WITH SAID WHEEL, AN OSCILLATORY PIVOTED ESCAPEMENT LEVER WITH CONNECTED PALLET BLADES OPERATIVELY ENGAGING SAID ESCAPEMENT WHEEL TO CONTROL ITS ROTATIONAL MOVEMENT, SAID ESCAPEMENT LEVER BEING MAGNETICALLY-POLARIZED WITH OPPOSITE MAGNETIC POLES AT THE OUTER FREE ENDS THEREOF AND BEING MOUNTED TO OSCILLATE ABOUT A FIXED PIVOT AXIS NORMAL TO THE PLANE THEREOF, MEANS PROVIDING SPACED MAGNETIC POLES IN SAID PLANE IN SPACED RELATION TO THE OUTER POLAR ENDS OF SAID LEVER AND OF LIKE POLARITY THEREWITH FOR APPLYING A MAGNETIC REPELLING FORCE THERETO AT EACH END WITH EACH OSCILLATORY EXCURSION THEREOF, SAID MEANS INCLUDING TWO PERMANENT BAR MAGNETS MOUNTED IN OPPOSED SPACED END-TO-END RELATION TO EACH OTHER AT EACH OUTER POLAR END OF THE LEVER ON OPPOSITE SIDES THEREOF, AND RELEASABLE MEANS FOR HOLDING THE LEVER IN A LOCKED POSITION AT THE END OF ONE OSCILLATORY EXCURSION WITH THE MAGNETIC REPELLING FORCE ACTING UPON THE LEVER AT SUBSTANTIALLY MAXIMUM MAGNITUDE, SAID RELEASEABLE MEANS BEING RESPONSIVE TO EXTERNALLY APPLIED FORCE RESULTING FROM ACCELERATED MOVEMENT OF SAID MECHANIMS AND ACTING IN A PREDETERMINED DIRECTION WITH RESPECT TO THE PIVOT AXIS THEREOF. 